Re: inner class scope issues

From:

Lew <noone@lewscanon.com>

Newsgroups:

comp.lang.java.programmer

Date:

Tue, 24 Mar 2009 00:07:42 -0400

Message-ID:

<gq9mag$3ch$1@news.albasani.net>

Mike Schilling wrote:

Lew wrote:

There is a subtle consequence of this that came up in another thread.
Consider an inner class that extends its outer class, as it might if
the outer class is abstract with a factory method. An inner-class
method with the same signature as one in its inherited containing
class only overrides the outer/super method if the outer/super method
has at least package-private access. If the outer method has private
access, the inner method does not override it.

You're right, this is subtle. The rule is

1. Private methods are not virtual and thus can't be overridden.

It's somewhat tempting to think that the rule is

2. Private methods are not visible to descendent classes and thus can't
be overridden.

The fact that inner and nested classes, which *can* see the private methods,
still can't override them demonstrates that the correct rule is 1, not 2.

The exact statement in the JLS, s. 8.2, is

Members of a class that are declared private are not inherited
by subclasses of that class. Only members of a class that are
declared protected or public are inherited by subclasses
declared in a package other than the one in which the class is
declared.

<http://java.sun.com/docs/books/jls/third_edition/html/classes.html#8.2>

Also, s. 8.4.8.1
<http://java.sun.com/docs/books/jls/third_edition/html/classes.html#8.4.8.1>

Your summary (#1) is accurate and succinct.

--
Lew